How to make a redirect from a non-existent $_GET parameter?

Question

PHP

I have the following index.php structure , which is responsible for my $_GET addresses.
$param[0] is the first get parameter, say site.ru/news. Here I did a check for non-existent addresses where $param[0].
Now the task is to redirect to the main page from a non-existent $param, where it can be $param[0,1,2,3], for example site.ru/news[0]/good[1]/jek[2]/ass [3 - non-existent parameter, it is from it that you need to redirect to the main one.]

Answer 1

You need to send 301 HTTP response: www.kobzarev.com/programming/301-moved-permanently.html

<?php
header("Location: http://www.example.com", true, 301);
exit();
?>